Home > Publications database > Antikörper gegen Membranproteine der Cephalopoden-Sehzell-Membran als Mittel zur Untersuchung des Transduktionsprozesses der Evertebraten-Lichtsinneszelle |
Book/Report | FZJ-2018-02829 |
1988
Kernforschungsanlage Jülich, Verlag
Jülich
Please use a persistent id in citations: http://hdl.handle.net/2128/18448
Report No.: Juel-2175
Abstract: In invertebrate photoreceptors signal transduction is not as well investigated as in bovine rod outer segments (Stryer, 1981). The initial event in both vertebrate andinvertebrate photoreceptors is the photoisomerisation of the chromophor of the photopigment rhodopsin. There is circumstantial evidence for a G-protein beeing the target enzyme for the active metarhodopsin: There is an intrinsic GTPase activity that is induced by blue and suppressed by red illumination in musca eyes (Blumenfeld et al, 1986) and also a light-dark difference in GTPase activity in squid photoreceptors (Saibil & Michel-Villaz, 1984). Blumenfeld et al. (1986) showed that the light activated GTPase activity in fly (musca) photoreceptors is assoziated with a long lasting excited state of metarhodopsin. This metarhodopsin seems also to be responsible for a prolonged depolarizing afterpotential in fly photoreceptors (Hamdorf & Razmjoo, 1977 and 1979 / Hamdorf, 1979). Injections of GDP$\beta$-S, a poorly hydrolysable analogues of GDP into the ventral photoreceptor of $\textit{Limulus}$ depress the sensitivity of the cells to light (Bolsover & Brown, 1982). Also a light induced binding of a stabel GTP analogue, GTP-$\Gamma$-S, was shown in squid ($\textit{L. opalescens, L. pealei}$) microvillar photoreceptor membranes (Vandenberg & Montal, 1984). Moreover photoexcited rhodopsin of squid and octupus photoreceptors can trigger the intrinsic GTPase activity of mammalian transducin in the absence of bovine rhodopsin (Vandenberg & Montal, 1984 / Saibil & Michel-Villaz). Furtheron a 46 kDa protein exhibits limited sequence homologies to transducin (Saibil & Michel-Villaz, 1984). These evidences indicate the involvement of a G-protein also in the invertebrate transduction process. [...]
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